In my U.S. Pat. No. 4,649,992 a device is described in combination with a catheter which is basically a compression spring retained between a partially inflated balloon and an abuttment immediately behind the balloon on the catheter shaft. The intent is to transport the spring prosthesis in this manner to the desired location and then after a successful angioplasty procedure release said spring prosthesis by totally evacuating said balloon, thus allowing said spring prosthesis to expand linearely and stay in place while the balloon catheter is withdrawn. This method is quite simple and its simplicity is very attractive; however it has some drawbacks. One an and foremost is the fact that the spring has a fixed diameter and as such is unable to fully conform to the inside wall of the vessel which at times is quite tortuous and thus could conceivably create a somewhat turbulant flow of blood, and possible thrombosis could in some cases result. Other Patents, eg. U.S. Pat. No. 4,553,545 teaches a different method where a relatively complex mechanical rotating device and co-axial cables are employed to achieve the necessary means to change the diameter of the implanted stent to a larger dimension at the point if implant. Still other Patents, eg. U.S. Pat. No. 3,868,956 describes a method wherein a temperature responsive metalic device is used and expanded after implant using external heat sources. All of the above mentioned devices present drawbacks of various magnitudes including blood coagulation and possible thrombosis, and considerable complexity of procedure.
In angioplasty procedures at this time, in many cases restenosis occures soon thereafter, which requires a secondary procedure or a surgical bypass operation. The implanted prosthesis as described herein will preclude such additional procedures and will maintain vascular patency indefinately.
Depending on the size used, the stent according to this invention can also be efficacious in other similar applications, such as: Repairs of aneurysms, support of artificial vessels or liners of vessels, innitial repairs of dissections and mechanical support to prevent collapsing of dialated vessels. Still many other and similar applications will be satisfied by this invention without departing from the basic premise and concept.
This stent and the method of its use particularely allows a single procedure to combine the essential angioplasty and a simultaneous implant of a permanent prosthesis designed and intended to prevent restenosis and further complications arising therefrom, also reducing the risk factor and trauma for the patient.
Other reference publications:
1. Self-expanding metalic stents for small vessels Radiology 1987--162.469-472. PA0 2. Flexible Balloon-expandable stent for small vessels Radiology January 87. PA0 3. Intravascular stents to prevent occlusion and restenosis after transluminar angioplasty, N.E.J. of M. Mar. 19 1987. PA0 4. U.S. Pat. No. 4,580,568 Percutaneous endovascular stent. PA0 5. U.S. Pat. No. 4,503,569 Transluminarely placed expandable graft prosthesis, Dotter 1985. PA0 6. U.S. Pat. No. 4,649,992 Catheter arrangement having a variable diameter tip and spring prosthesis, Wiktor 1987 PA0 7. U.S. Pat. No. 4,681,110 Catheter arrangement and blood vessel liner, Wiktor 1987
All of the above references describe and teach various methods of providing or otherwise offering and introducing stents of different types and designs for applications similar to the one described herein in this invention.